A new experimental technique is presented to measure the soot particle absorption function and the gas temperature. The approach is based only on LII and requires measuring soot particles' peak temperature at two different laser fluences. A theoretical investigation of the technique indicates the necessity to work at low fluences with two fluence values as spread as possible. Also, it shows that the underestimation of the absorption function grows with decreasing particle size. The technique has then been applied to a weakly sooting methane/air laminar diffusion flame. A coherent estimation of the absorption function is found, proving the approach's feasibility.